This is it, @Gowtham_Rao. These should be two phenotypes: One for hypertensive crisis, and another one for the chronic condition of hypertension that leads to such crises or to a chronically high blood pressure.
Same thing: For the crisis, it’s the measurement of a low BP, or the end of the visit, or the administration of a slew of hypertensive drugs, or just a couple days as a means of last resort. It doesn’t really matter exactly when it ends, you just need to have some reasonable end date so you can have distinct crises for calculating their rates. For the ongoing hypertension as a disease, there is no end needed. We won’t calculate incidence rates of those conditions beyond the first onset (which is why those incidence rates are really proportions of patients in the population).
My problem with all this, as declared elsewhere, that we bury this in some text. We don’t make categories explicit:
- Acute onset conditions
- Chronic condition with flares
- Chronic conditions with a cure
- Chronic conditions without a cure
The criteria would be very different for these.
We also don’t seem to classify our criteria set:
- Improvement over low specificity (e.g. through repetition)
- Improvement over low sensitivity (e.g. through combination with diagnostic procedure)
- Improvement of index date (e.g. through combination with diagnostic procedure)
- Re-diagnosis because we trust neither of the above (e.g. using BP measurements for hypertension)
- Mixture thereof
And then there is the avoidance of some confounder, as @Kevin_Haynes mentioned, which should be absent for any of this. That’s for the studies.